The present invention relates to an electronically shifted four wheel drive system for an automotive vehicle, and more particularly to a system and method for fault management with respect to the faults in position sensing device and the shift device.
Four wheel drive systems include Electronically Shifted and mechanically shifted four wheel drive systems. Certain of such electronically controlled systems may be shifted on the fly; meaning thereby there is a microprocessor that controls the shifting. Alternatively, there are Mechanical shift on the fly (MSOF) systems that operate with a manual lever and don""t have an electronically controlled unit.
In an electronically controlled system, certain faults are detected and the microprocessor controls the shift device to take appropriate action in the presence of such faults. However, faults in position sensing device and shift device are very important and typically are not addressed in a robust manner. It would be desirable to provide a system and method which adequately manages faults in position sensing device and shift device to ensure logical and safe response.
Accordingly, the present invention provides a system and method to manage sensing device faults and shift device faults. In a system according to the present invention, a micro-processor is provided to enable accurate, safe, reliable, and fault-tolerant operation. More particularly, the present invention provides fault management methods for different faults in position sensing device and shift device.
According to the present invention, a system and method are provided for taking appropriate action in the face of faults detected in the system components, namely, position sensing device and the shift device.